Create a single build for the NVDA addon #104

Apparently it is possible to have one deliverable that contains a 32 bit and 64 bit pyd file and have the code choose which to load on start up. An example can be found here, although that example uses sys.platform == 'win32', which is not a good method to decide.

See nvaccess/addon-datastore#10710 (comment) for a little more discussion.